Manish has to secure 40% marks to pass his B.tech final exams.
He got just 40 marks and failed by 40-marks.

What is the maximum marks?

Name a key which is hardest to turn.

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

What is the next number in this matchsticks series riddle?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

Can you replace the question mark with the correct number in the below table sequence?

Make the seating arrangement of 10 children in such a way that there are 5 rows with 4 children in each row.

Can you name an animal whose killing cannot be performed without spilling your own blood?